Exact positioning of isocurves

Hi, I am wanting to be able to position some isocurves to exact positions on my object, like be able to define a certain distance from the center or from another isocurve, or even to position one at the midpoint between 2 existing isocurves. Is there a way to do that?

This would help me enormously to accurately control where I split the object to connect with another object…

Any ideas?

Hi Michael - do you want a free curve that is extracted from a surface at isocurves at these locations (ExtractIsocurve) or do you want the surface to somehow have isos where you need them? If the latter, why?


Hi Pascal, I want to have the isos where I need them, either numerically positioned from another one or from a certain point on the object so I can accurately define where it is split and connect/blend with another object. Is there no way to do this?

Hi Michael - isocurves reflect the UV parameterization of the surface, not necessarily any 3d distances or arrangement. I think you may get something useful if you ExtractIsocurve with History on. - that curve will update with edits to the surface, however, that does not mean that if you put it X units away from an edge, say, it will stay at that distance.

ExtractIso_History.3dm (32.5 KB)


Do things like symmetry planes and axes exist in rhino? This would help immensely trying to position the same isocurve on the opposite side of a midplane for example when needing to split the surfcae to attach to another object…
I don’t currently see a workflow that allows for any accuracy at all when positioning isocurves.

Hi Michael - not without some helper geometry I guess - can you post an example? What you have and what you want to get to (approximately) ?


Another option or 2 could be to run Contour command. Or Section command . Or make some planar surfaces where you want the iso lines and run Intersect. Any of these might be of use.—Mark